Flowering Time in 5-Azacytidine Mutants of Oilseed Flax (Linum usitatissimum L.).

Oilseed flax (Linum usitatissimum L.) grows vegetatively for 45-60 days, flowers for 15-25 days and matures over the next 30 to 40 days in Western Canada. However, both yield and seed quality can be severely affected if the first fall frost occurs before crop maturity is reached. Previous research has shown that imbibing flax seeds from the old cultivar “Royal” with the DNA hypomethylating chemical 5-azacytidine (5-azaC) induced heritable reduction in time to flowering and plant height. Populations were developed to study the effects of 5-azaC on flowering time and height with the goal of developing lines suited for the short Saskatchewan growing season. The first population consisted of 98 M₂ lines derived from 5-azaC imbibed CDC Sorrel seeds (a popularly grown oilseed flax variety). The second population consisted of 16 F₂ lines derived from reciprocal crosses between CDC Sorrel and stably inherited, early flowering M₉ Royal oilseed flax obtained through 5-azaC mutatgenesis. These lines were grown in progeny rows at a Crops Research farm near Saskatoon, SK, in 2012. Field evaluation indicated that M₂ CDC Sorrel flowered 48-64 days after seeding, while the control lines (untreated CDC Sorrel) flowered 54 days after seeding. M₂ lines plant height varied between 60-85 cm, while the untreated CDC Sorrel was 74 cm in height on average. Flowering times for the F₂ lines were intermediate between the mutant-derived parental lines (51, 48, 47, 48 days after seeding for Royal, RE1, RE2 and RE3, respectively) and the untreated parent, CDC Sorrel, at 61 days. The heights for the F2 lines also exhibited an intermediate phenotype.  Our preliminary field evaluation indicated that 5-azaC increased variability in days to flowering and plant height and can be inherited transgressively once the traits are stably incorporated. Further work planned includes advancement and selection of M₃ and F₃ lines and mutagenesis of other CDC oilseed flax varieties.